Don't No What To Do

Iv been married for 16 years and for the last five years iv not been happy, my husband isn't the same man I fell in love with we have four kids together and I feel he doesn't treat them the way he should iv tried to work things out with him and he says he would change but it only last a few days then he's back to old self, we do nothing as a family it's the same day in and day out, a year ago I met this wonderful man we work together every day and soon started seeing each other I forgot what it was like to be loved we have spent weekends away together and he has showed me how to live again, I want to start a life with man as wer both in love with each other and I know he would treat my kids like his own but I just don't no how to go about leaving my husband I'm scared incase he does something silly or my kids won't take to my new partner all I want is to be happy again and this new man does I just don't no what to do , do I stay for his sake or do I be happy with this other man .